The present invention refers to a support device for a centrifugal separator having a centrifuge rotor, which is provided in a frame member to be rotatable about an axis of rotation by means of a bearing member, said support device comprising a support element provided between the bearing member and the frame member and arranged to absorb relative movements between the centrifuge rotor and the frame member, said support element comprising an inner mounting portion, which is arranged to be essentially immovable in relation to the bearing member, and an outer mounting portion, which is arranged to be essentially immovable in relation to the frame member.
The present invention will be described in connection with a so called upper bearing support of a centrifugal separator. However, it is to be noted that the invention is applicable also to other bearing supports of centrifugal separators. Such conventional bearing supports are essentially of two types, namely bearing supports in which springs apply a force to friction buffers and bearing supports in which a dampening rubber element is included.
These known bearing supports comprise many details making them complicated and expensive. The dampening properties of the friction buffers and of the rubber elements are difficult to calculate. On the friction surfaces being dampened through friction, coatings (coke) are formed, which change the dampening properties and result in a great risk of jamming. The dampening properties of the rubber material are difficult to predict and change over the time. In the friction buffers, wear particles are formed, which reduce the working life of the bearing support. The heat transfer is poor in these known bearing supports, since rubber has a low heat conducting capability and the friction surfaces of the friction buffers deteriorates the heat transfer.
WO 89/10794 discloses an example of such a known bearing support for a centrifugal separator having a centrifuge rotor which is rotatable in a frame member by means of a bearing member. The bearing support comprises a number of support elements which extend radially outwardly from the bearing member and which each encloses a spring member of a helical spring type. These support elements are arranged to permit relative radial movements between the centrifuge rotor and the frame member by being moveable in a hole of the frame member. The friction, which exists between the contact surfaces of the support element and adjacent elements, results in a dampening of the radial movement and a heat development, which is of course not desirable. U.S. Pat. No. 2,487,343 discloses such a similar bearing support which in addition comprises a number of spring members extending axially and thus being arranged to permit axial relative movements between the centrifuge rotor and the frame member. DE-C-558 937 and GB-C-9002 disclose further examples of known bearing supports having helical springs extending in a radial direction. These known bearing supports have a highly complicated construction with a great number of components included, which of course makes the manufacture and the mounting of the bearing supports labor intensive and expensive, and in addition makes it difficult to transfer heat away from the bearing member.
GB-A-1 397 172 discloses a support device of the type initially defined for a centrifugal separator with a centrifuge rotor which is provided in a frame member to be rotatable about a rotational axis by means of a bearing member. The support element of this known support device comprises a first group of at least three elastic components which are arranged to oscillate merely in radial direction with respect to the rotational axis, a second group of at least three elastic components which are arranged to oscillate merely in an axial direction, and a rigid member connecting the elastic components of the first and second groups. Certainly, the known support element may be manufactured as an integrated unit but it has a highly complicated shape since it requires different components for different functions. Furthermore, the axial extension of the known support element is relatively long.
SE-C-54 165 discloses another type of support element for a centrifugal separator, which is provided between a frame member and a bearing bushing for a rotating shaft. The support element is designed as a plane or corrugated membrane and arranged to permit an oscillating movement of the bearing bushing and the shaft, at the same time as a radial relative movement between the frame member and the bearing bushing is excluded.